1. Field of the Invention
The present invention generally relates to camera modules and, more particularly, to a camera module which can be used with a portable electronic device such as a mobile phone or a PDA (personal digital assistant).
2. Discussion of the Related Art
With the rapid development of multimedia technology, use of digital devices such as digital still cameras (“still cameras”) and digital video cameras (“video cameras”) has become wide-spread in many countries. Mobile phones have improved both the number and the quality of the functions they can perform. Therefore, digital devices performing a wide variety of functions have been combined with mobile phones.
Currently, camera modules employed in most mobile phones and PDAs have fixed focal length and do not include an optical zoom function. In such a camera module, a focal length (represented by “f”) is unchangeable. Thus, if we want to take pictures of objects with different apparent object distances (represented by “u”), i.e. an apparent distance between an object and a lens of the camera module, an image distance (represented by “v”), i.e. an apparent distance between an image and a lens of the camera module, should be changed according to the formula 1/u+1/v=1/f. The image distance is often changed by changing a position of the lens or the image sensor. However, in this manner, changed length of the image distance is generally same as the changed distance between the lens group and the image sensor. Therefore, the camera module including the lens and the image sensor needs to occupy a large space to allow changing a position of the lens group or the image sensor. Thus, the camera module has a large size which makes it unsuitable for use in mobile phones and PDAs.
What is needed, therefore, is a camera module, which overcomes the above-described problems.